The use of polymeric film bases for carrying photographic layers is well known. In particular, photographic elements which require accurate physical characteristics use polyester film bases, such as poly(ethylene terephthalate) or poly(ethylene naphthalate) film bases. In fact, polyester film bases, when compared with commonly used cellulose ester film bases, are dimensionally more stable and more resistant to mechanical stresses under most conditions of use.
The formation of static electric charges on the film base is a serious problem in the production of photographic elements. While coating the light-sensitive photographic emulsion, electric charges which may accumulate on the base can discharge, producing light which may be recorded as an image on the light-sensitive layer. Other drawbacks which result from the accumulation of electric charges on polymeric film bases include the adherence of dust and dirt and coating defects.
Additionally, photographic elements comprising light-sensitive layers coated onto polymeric film bases, when used in rolls or reels which are mechanically wound and unwound or in sheets which are conveyed at high speed, tend to accumulate static charges and record the light generated by the static discharges.
The static-related damages may occur not only during the manufacturing process but also in the subsequent handling of the film prior to processing during which the photographic image is developed and the excess silver halide is removed.
Several techniques have been suggested to protect photographic elements from the adverse effects of static charges.
Matting agents, hygroscopic materials or electroconductive polymers have been proposed to prevent static buildup, each acting with a different mechanism. However, matting agents cause haze, dust and dirt problems, hygroscopic materials cause sheets or films to stick together or with other surfaces, and electroconductive polymers frequently are not transparent when coated with conventional binders.
Layers containing vanadium oxide particles have proved to be useful classes of antistatic protection layers in the field of imaging technologies. U.S. Pat. No. 4,203,769 provided an initial disclosure of vanadium oxide coatings used on photographic substrates to provide antistatic protection. Many subsequent patents provide teachings of improved vanadium oxide formulations and binder compositions which improve the performance and stability of the vanadium oxide antistatic layers on imaging media. Amongst these patents are U.S. Pat. Nos. 5,203,884; 5,322,761; 5,372,985; and 5,407,603 which disclose processes for manufacturing improved vanadium oxide colloidal dispersions, flexographic printing plates with vanadium oxide antistatic layers, and thermal transfer elements with vanadium oxide antistatic layers. U.S. patent applications Ser. No. 07/893,279 bearing attorneys docket no. 48349USA1A and 08/277,097 bearing attorney's docket no. 49675USA6B disclose improved binder systems for vanadium oxide antistatic layers.
As increased speed in manufacturing, conveying and processing a film is important in the photographic industry, improvement in antistaticity of photographic layers is strongly desired. It is also desirable that the antistatic element is readily applied either as a subbing layer during the base making operation or as a part of the layer construction making up the photographic element. The present invention satisfies these requirements.